Friction stir welding (“FSW”) of metals has been used to attach weldable materials to one another in a solid state joining process. FSW uses the motion of a pin pressed against the surface of a weldable material to generate heat and friction to move the weldable material. The material may plasticize and physically stir together with a second material to which the first material may be welded. For example, a pair of metal plates may be positioned adjacent one another with their respective edges abutting one another forming a seam between the two plates. A pin, a pin and shoulder, or other “FSW tip” may be rotated in contact with the two plates. A force may be applied to the FSW tip to urge the FSW tip against the two plates. The FSW tip may be moved along the seam to stir the edges of the two plates together. The physical process of mixing material from the plates may join the plates. FSW of metals may include friction stir joining (“FSJ”), friction stir extrusion (“FSE”), and other techniques including the plasticization of weldable material without a liquid state. In another example, two weldable materials may be stacked relative to one another and to an FSW tip, and the FSW tip may be rotated and plunged into the stack of the two materials to stir material from the top plate and bottom plate together and bond the two weldable materials together.
FSW may join weldable materials in a solid-state process that avoids many of the potential defects of other welding processes. For example, FSW may produce a bond region along the path of the tool that is generally indistinguishable from the original material. FSW may be performed without the inclusion of an additional material or use of shield gasses. Some welding methods, such as metal-inert gas (“MIG”) welding, may introduce an additional material to create a bond. Other welding methods, such as tungsten-inert gas (“TIG”) welding, may use a non-consumable contact point to heat one or more workpieces. However, the heating may cause the one or more workpieces to attain a liquid phase and risk a phase change in the one or more workpieces. A phase change may compromise the integrity of the bond and, potentially, the workpiece, itself. To limit the possibility of a phase change or other reaction, TIG welding and similar processes utilize an inert gas “shield” around the contact area.
FSW may, therefore, provide more controllable bonds in various applications. The predictability of FSW may be desirable during the manufacturing and/or assembly of structures or devices that experience high forces during use in environments or applications in which the structure or device may be inaccessible by operators. For example, a downhole tool may be delivered hundreds to thousands of meters through a to wellbore during a drilling application. A downhole tool may include stabilizer pads that have wear resistant material affixed thereto. The wear resistant material may be a non-weldable material such as a high temperature ceramic. Conventional welding techniques may be insufficient to affix a non-weldable material to a downhole tool.